The influence of the substrate temperature on the preparation of thin film In2Te3

An optimum substrate temperature T_o of 453 K was found for the preparation of thin film In₂Te₃ by electron beam evaporation. Films prepared at this temperature are stoichiometric and exhibit a maximum hole mobility of 48 cm² V^-1s^-1 and a maximum hole concentration of 4.2 × 10¹⁸ cm^-3. These observations can be explained on the basis of the Vincett-Barlow-Roberts theory which predicts a value for T_o/T_b, where T_b is the boiling point, of 0.3. The electrical activation energies of the films were also determined and are discussed in terms of the possible defects present.     

Prototypes from standard user interface management systems

An explanation is given of showing a computer what to do by directly manipulating objects, as opposed to giving it instructions using a programming language. The authors demonstrate how showing can take advantage of a standard user interface and the consistency of a user interface paradigm. They discuss prototyping in the Oregon Speedcode Universe, a programming system for writing programs without programming languages     

On Methods of Constructing Sets of Mutually Orthogonal Latin Squares Using a Computer. II

A new class of triplets of mutually orthogonal latin squares is derived. These are the consequence of attempts to extend the results described in Part I of this paper which appears in Technometrics, 1960, Vol. 2, No. 4, p. 507.     

In vitro biological and tribological properties of transparent magnesium aluminate (Spinel) and aluminum oxynitride (ALON<Superscript>®</Superscript>)

The purpose of this first generation investigation is to evaluate the in vitro cytotoxicity, cell-materials interactions and tribological performance of Spinel and ALON^® transparent ceramics for potential wear resistant load bearing implant applications. Besides their non-toxicity, the high surface energy of these ceramics significantly enhanced in vitro cell-materials interactions compared to bioinert commercially pure Ti as control. These transparent ceramics with high hardness in the range of 1334 and 1543 HV showed in vitro wear rate of the order of 10^?6 mm³ Nm^?1 against Al₂O₃ ball at a normal load of 20 N.     

Tuning the dispersion of multiwall carbon nanotubes in co-continuous polymer blends: a generic approach

Melt-mixed blends of polyamide 6 and acrylonitrile-butadiene-styrene (PA6/ABS) with multiwall carbon nanotubes (MWNTs) were prepared with the intention to develop conducting composites. A generic strategy, namely specific interactions combined with reactive coupling, was adopted to facilitate and to retain the 'network-like' structure of MWNTs during melt-mixing. This was facilitated by the sodium salt of 6-amino hexanoic acid (Na-AHA) and certain phosphonium based modifiers, where it was envisaged that these modifiers would establish specific interactions (either 'cation-π' or 'π-π' ) with the 'π-electron' clouds of MWNTs, as well as restricting them in the PA6 phase of the blends via reactive coupling. This route eventually led to a remarkable increase in the electrical conductivity and dielectric constant in the blends with MWNTs. Raman, FTIR and TEM investigations further supported these observations.     

A digital signal processing laboratory for undergraduates

An undergraduate level laboratory on digital signal processing (DSP) is described. The equipment used and samples of student experiments are described in detail. The lab is based on the TMS320 digital signal processor and is equipped with spectral analysis and audio signal processing capabilities. The primary purpose of the lab is to supplement a course on digital filter design and implementation. However, it can also be used for senior design projects involving DSP applications     

Power electronics and motion control-technology status and recenttrends

Power electronics and motion control have emerged as very important technologies in the recent trend of industrial automation. This work reviews the technology status and trends in power electronics and motion control with emphasis on AC machine drives. A comprehensive review of power semiconductor devices, power converter circuits, machine drives, and various motion control techniques is included. The effect of expert systems, fuzzy logic, and neural networks on intelligent motion control is also discussed     

Three-Phase AC Power Control Using Power Transistors

A three-phase ac power control circuit using power transistors which operate in a high-frequency chopping mode is described. The circuit is capable of handling several kilowatts of power at any lagging load power factor angle and the output voltage can be smoothly controlled from zero to full supply voltage. The circuit has inherently fast response and the high-frequency ripple at the output is easily filtered. The development, study, and experimental evaluation of the circuit with resistive and induction motor loads is described.